Milk glass, the nickname given to opaque white glass in a variety of patterns, was produced around the world for thousands of years prior to the mid-1800s when it became a commodity in the United States. Milk glass manufacturers in America were concentrated in Eastern Pennsylvania, in fact.
The popularity of this glass piqued around 1895-1910, according to The Collector's Encyclopedia of Milk Glass by Bill and Betty Newbound (now out of print but available through used booksellers), but there was a big milk glass revival in the 1940s and '50s.
Those pieces are the examples most often found by collectors today.
Popular Motifs in Older American Milk Glass
The dolphin, which actually looks a lot more like a fish than a porpoise, was used to form the stems of candlesticks, compotes and other items reflecting the Empire style popular during the mid-1800s (although it has seen many revivals in glass over the years). After the Civil War era, various animals and birds were popularly molded into in all types of pressed glass, including milk glass.
Draping patterns reflected the mourning festoons on milk glass memorial pieces for Presidents Lincoln and Garfield during the 1800s. The turn of the 19th century saw the Spanish-American War commemorated with covered dishes shaped like ships or busts of Admiral Dewey. The laying of the Trans-Atlantic cable had an influence on glass designs, too, and resulted in cable motifs. "The whole history of our country can be followed in its glass," wrote the Newbounds.
Newer Milk Glass of the 1940s and '50s
Most of the milk glass collectors encounter today was made by Westmoreland Glass and Fenton Glass. Wesmoreland began making milk glass in the 1920s, while Fenton started in the 1940s. Westmoreland's Paneled Grape pattern, which is similar to a line produced in the early 1900s by another company, is the most prolific but their Beaded Grape, Old Quilt, and Roses and Bows patterns can also be found in antique shops today.
Fenton utilized hundreds of their varied molds in milk glass production. One of the most popular was Silver Crest, which has a milk glass body with a ruffled edge fashioned of clear glass. Other colored edges were attached to milk glass such as Peach Crest and Emerald Crest. Fenton's Hobnail pieces were touted as their "oldest, most popular pattern" in milk glass marketing materials and these are readily found by collectors today.
Kemple glass works made "authentic antique reproductions processed by hand" that look like old pressed glass pieces as well. The glass looks more modern and whiter in comparison to older pieces in most instances.
Other companies such as Jeannette Glass, Fostoria, Indiana Glass, and L.E. Smith Glass also produced milk glass lines. L.E. Smith's Vintage Grape pattern is sometimes confused with Paneled Grape, but it doesn't have the angular panels behind the grape motif when compared to Westmoreland pieces. Indiana's Harvest Grape is closer in style, but the "panels" in that pattern are not as angular as Westmoreland's.
Distinguishing Old from New
Take care when learning to distinguish new milk glass from old - which includes differentiating Victorian-era milk glass from mid-1950s pieces along with those made during the past 20 years or so (see information on molds being reused below).
There are a number of commonly referenced attributes of older glass that can sometimes be found in new glass as well.
Some glass dealers swear older pieces are opalescent around the edges, but newer pieces can have this same type of look. Other sellers will tell you that three-part molds (indicated by three mold lines found around the piece) are old, but newer glass was made with this type of mold, too. Some people will remark that an indention shaped like a shell present in the base indicates older glass. This, according to the Newbounds, occurs when glass is poured into a mold too slowly, and it can be present in new glass as well.
Some glass dealers also assume that all painted milk glass is old, but that's not a hard and fast rule. And while testing with a black light will reveal cracks and repairs with some types of glues, making sure a piece glows under a fluorescent bulb should be one confirmation of age and not the only measure.
So how do you know if a piece is old? The long and short of it is to study both new and old glass. Look at documented pieces of older glass in books and catalogs. Hold as many pieces as possible at glass shows and ask questions about them. Note details about older patterns in comparison with new. There is a "feel" of older glass compared with new that comes with experience. Keep learning and you will master distinguishing old from new over time.
Milk Glass "Reproductions"
Westmoreland Glass Company, in business from 1890 to 1984, made milk glass beginning in the 1920s. After the company closed, its molds were sold off. Before Imperial Glass Corporation closed in 1984, the firm had acquired a number of Cambridge Glass Company molds. When Imperial's molds were auctioned off both their own mold designs and those formerly used by Cambridge ended up in the hands of both glasshouses and collectors clubs.
Collectors clubs, like the Cambridge Collectors of America and Imperial Glass Collectors Club, often buy glass molds when they come on the market in an effort to protect the integrity of collectible glass. If they commission a piece to be made from the molds they own, they are clearly marked as commemorative pieces.
Glass manufacturers holding the Westmoreland and Imperial molds - Boyd's Crystal Art Glass, Summit Art Glass, Viking Glass, and Blenko Glass Company, among others - have made many pieces of glass with those molds since the mid-1980s. It's nothing new for molds to change hands from glasshouse to glasshouse, of course. It also happened back in the peak years of milk glass production, as noted in the Newbound's book.
Since these companies own the molds, new pieces are technically not reproductions (although some collectors and dealers do see them that way) like imports made from new molds made to mimic old ones. Nevertheless, if you want to make sure you're buying antique or vintage glass it's wise to study up on what these companies are making with the old molds they purchased and follow where they end up in the future.
However, keeping up with them is no easy task as more and more glass companies close their doors as Fenton did in 2011.